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arXiv 1607.01770cond-mat.supr-concond-mat.str-el
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4 e电荷超导体的Majorana量子Monte Carlo研究

Charge-4e superconductors: a Majorana quantum Monte Carlo study

Yi-Fan Jiang, Zi-Xiang Li, Steven A. Kivelson, Hong Yao

摘要:

电荷-4e超导体的许多特性仍然未知,因为即使是描述它们的“平均场哈密顿量”也是一个相互作用模型。在这里,我们引入一个相互作用模型来描述一个电荷-4e超导体(SC)在超导相深处,并探讨其性质使用量子蒙特卡罗(QMC)模拟。QMC是无符号问题的,但只有当马约拉纳表示。作为化学势的函数,我们观察到两种截然不同的行为:一个“强”四分相,其中电荷-4 e四重态紧密结合(像分子),使电荷-2 e配对不会发生,即使在温度$T \to 0$限制,和一个“弱”四分相,其中进一步过渡到一个电荷-2 e超导相发生在一个较低的临界温度。类似的问题出现在一个假定的Z4自旋液体与伪费米表面,并在表征电荷-2e SC与“奇频率配对”(或等效的“复合序参量“)和金属自旋向列。在某些情况下,我们还确定了一个稳定的T=0电荷-4e SC相与无带隙节准粒子。我们进一步讨论了我们的结果可能与1/8掺杂LBCO的各种实验观察。

英文摘要:

Many features of charge-4e superconductors remain unknown because even the "mean-field Hamiltonian" describing them is an interacting model. Here we introduce an interacting model to describe a charge-4e superconductor (SC) deep in the superconducting phase, and explore its properties using quantum Monte Carlo (QMC) simulations. The QMC is sign-problem-free, but only when a Majorana representation is employed. As a function of the chemical potential we observe two sharply-distinct behaviors: a "strong" quarteting phase in which charge-4e quartets are tightly bound (like molecules) so that charge-2e pairing does not occur even in the temperature $T \to 0$ limit, and a "weak" quarteting phase in which a further transition to a charge-2e superconducting phase occurs at a lower critical temperature. Analogous issues arise in a putative Z4 spin-liquid with a pseudo-Fermi surface and in characterizing charge-2e SCs with "odd frequency pairing" (or equivalently with a "composite order parameter") and metallic spin-nematics. Under certain circumstances, we also identified a stable T=0 charge-4e SC phase with gapless nodal quasiparticles. We further discuss possible relevance of our results to various experimental observations in 1/8-doped LBCO.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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